I have the USB3-VGA adapter on a Windows 8.1 laptop. There are 3 monitors: the laptop itself, the monitor attached using VGA, and the monitor using the USB3-VGA adapter.
Throughout the day I have situations where all of the monitors start blinking off and on, sometimes for several minutes. Sometimes this happens when the monitor’s background picture changes automatically (by using the option in Windows to have backgrounds changing periodically). At other times it happens when I drag a window to the USB3-VGA monitor.
Sometimes I have no problems for a day or two, but at other times I have to endure long periods of screens flipping off and on. It stops as soon as I unplug the USB3-VGA adapter from the laptop. I plug it back in, and it resumes flipping.
While it is flipping, Windows is making the same sound as if I were manually unplugging and replugging the adapter from the USB port. In my case it is a chiming sound.